A conventional biometric information acquisition device disclosed in Patent Document 1 detects a sign of drowsiness of a driver driving a vehicle and monitors his/her biometric conditions.
More specifically, the device described in Patent Document 1 has six small air pouches, which have no air circulation therebetween, dispersedly disposed over the entire surface of a backrest portion of a seat of the vehicle. One of the pouches located near the lumber area of the seated person has a sensor for measuring fluctuations in air pressure inside the pouch. Based on the measured fluctuations in air pressure, the device obtains time-sequence signal data including pulse waves of the aorta near the lumbar area of the seated person, provides signal processing on the time-sequence signal data, and detects a sign of drowsiness as biometric information.